Preparation of styrenes

ABSTRACT

THE VAPOR PHASE REACTION FOR PRODUCING STYENE FROM TOLENCE AND METHYL CHLORIDE IS PROMOTED BY METHYL BROMIDE, METHYL IODIDE, HYDROGEN BROMIDE, HYDROGEN IODIDE, BROMINE, AND IODINE.

United States Patent Office 3,636,182 Patented Jan. 18, 1972 3,636,182PREPARATION OF STYRENES George J. Kallos, Saginaw, and Che-I Kao,Midland,

Mich., assignors to The Dow Chemical Company, Midland, Mich. No Drawing.Filed Nov. 14, 1969, Ser. No. 877,002

Int. Cl. C07c 15/10 US. Cl. 260-669 17 Claims ABSTRACT OF THE DISCLOSUREThe vapor phase reaction for producing styrenes from toluenes and methylchloride is promoted by methyl bromide, methyl iodide, hydrogen bromide,hydrogen iodide, bromine, and iodine.

BACKGROUND OF THE INVENTION This invention relates to a novel processfor producing styrenes from toluene or substituted toluenes and methylchloride in vapor phase, at elevated temperatures, using methyl bromide,methyl iodide, hydrogen bromide, hydrogen iodide, elemental bromine oriodine as promoters for the reaction. The promoters can be used singlyor in any combination.

Styrene and substituted styrenes are useful for making a variety ofpolymers and copolymers. The polymeric substances are useful in theproduction of molded articles, latex paints, synthetic rubbers, coatingsand the like.

In copcnding application Ser. No. 745,399 filed July 17, 1968 in thename of George J. Kallos, now US. Pat. No. 3,494,469, there is describeda process for making styrenes by reacting toluene or substitutedtoluenes with methyl chloride at 550-1200 C. to produce thecorresponding styrenes.

SUMMARY OF THE INVENTION It has now been found that if a .005 to .40mole of a promoter of the type described, based on the moles ofmethylene chloride, is added to the reaction mixture containing atoluene of the formula CIIzR where R is H, CN or phenyl and one or bothof X and Y is H, CH CH=CH CN, NCO, F, Cl, Br, phenyl or SO F, and themixture is heated to 550l000 C., sig nificant increases in conversionand yield of the desired styrene are obtained. The molar ratio of methylchloride to the toluene can range from 0.5 to 40, but it is preferredthat at least equimolar ratios and, more preferably, about 5 to 25 molesof methyl chloride per mole of toluene, be used for best results. Thecontact time will vary somewhat depending inversely on temperatures, buta range of .1 to sec. is operable, and a range of .2 to 1.4 sec. ispreferred.

The most desirable reaction temperature will also vary somewhatdepending on the particular toluene compound used and the specificpromoter employed. Usually, the conversion increases directly withincreases in temperature,

but above certain temperature range the specificity of the reaction isdecreased. However, in spite of the fact that yields of desired productare somewhat lower at any temperature above the optimum, the totalproductivity per unit time may still be high because of increasedconversion. The preferred temperature range is 650850 C. and mostpreferred is a range of 650800 C.

Reaction or residence time can be adjusted by varying the feed rates, bydiluting the reaction mixture with inert diluents, or by changing thevolume of the reaction zone, such as by using a reactor packed withinert solids. Preferably, the reaction mixture is diluted with a gassuch as steam, nitrogen, argon or carbon dioxide. The term inert meansthat the substance referred to is substantially unreactive with any ofthe components in the reaction mixture or product of reaction under theconditions specified. Average residence time for this mixture in thereaction zone is preferably 0.1 to 10 seconds, more preferably about 0.5to 3 seconds under the preferred temperature conditions. At the hightemperatures of 10001200 C. a residence time of microseconds may bedesirable to avoid excessive decomposition reactions. The reaction ispreferably run at or about atmospheric pressure or at autogenouspressure. Subatmospheric or moderate superatmospheric pressure may beused. Since the reaction in volves an increase in volume due to theproduction of HCl and other gaseous products, excessively high pressuresare not desirable. Because of the production of HCl the materials ofconstruction for the reaction system, particularly the reactor, shouldbe resistant to the corrosive effects of HCl and the reactor should alsoresist elevated temperatures. Preferably, the reaction zone is filledwith inert, heat and HCl resistant rings, balls, saddles of other formof packing to facilitate turbulence and heat exchange. However, thereactor can be an empty tube, if desired. The preferred material ofconstruction is a ceramic or silica based material.

The reaction efiluent contains the desired styrene, some unreactedtoluene, unreacted methyl chloride and some promoter or a derivativethereof. The effluent is condensed and the overhead which contains themethyl halides, any unreacted HBr, Br iodine or hydrogen iodide, smallamounts of methane and the HCl formed in the reaction. The gaseous phasecan be cooled to separate the hydrogen and methane as gases and theremainder can be liquified and can be recycled to the process. Theliquid condensate obtained by condensing the reactor effluent can besubjected to known separation means to recover any unreacted toluene,which can be recycled, if desired, and to recover and purify the styrenecompound such as by distillation or extraction or any other known means.

The examples which follow are intended to illustrate, but not to limit,the invention. All parts or percentages are by weight unless otherwiseindicated.

EXAMPLE I The reactor was a cm. long high silica glass (Vycor) tube,with an inner diameter of 1.9 cm. It was operated with and without highsilica glass rashig ring packing for control of contact time. Thereactor was placed vertically in an electric furnace, having two heatingsections, one 20 cm. and the other 55 cm. long. The 20 cm. sectionserved as a vaporizer and preheater and the 55 cm. section as thereaction zone.

Liquid reactants and water, when steam was the diluent, were fed to thetop by calibrated syringes. The gaseous components, the promoters, andnitrogen when used as the diluent, were also introduced into thepreheater.

A portable on-site mass spectrometer was used for monitoring thereaction. A vapor phase chromatograph EXAMPLE III The equipment andgeneral procedure of Example I were employed. In this series,m-tolylisocyanate was the In this series of runs the diluent wasnitrogen, the pro- 5 toluene p y and the PFOIIKmar was methyl Nitrogenwas used as a diluent. Steam should be avoided because of the reactivityof the isocyauate group. The preheater temperature was held at about 560C. for the first eight runs and at about 630 C. for runs 9 to 14,inclusive. hiding data from comparative te t i hi h no 10 T abulatedbelow are the data obtained in the tests, including the controls inwhich no promoter was used.

TABLE III Con- CHaCl/m- CHgBI] version, Yield, Reaction tolyliso- CHaCl,percent percent tempera- CHQCI, cyanate, molar Contact molar Molar turo,C. moles/hr. molar ratio ratio time, sec. basis basis Run and infra-redspectroscope were also used to analyze and identify the products.

The reactor efiluent was quenched with water or methylene chloride.

moter was methyl bromide, the toluene was o-tolunitrile and thepreheater temperature was held at about 500 C. for the first eleven runsand about 630 C. for the remaining runs. Tabulated below are the dataobtained in the runs, inc promoter was added.

40154838083 43 7 DmL H %Qm%m5 123 4 S a m u e e u m mfl W wd a m m s e 1m mw m e m e 11111111 .0 0 & W% .m P W m w A d N E 5 m c g z mmmhmmummmu L m o m w 00 0 0 0 0 0 0 0 0 m A 1 1 4 195 is X m mm m w mrw mwwwm55555490555565 E k m wm nm d m s n a mm n fififisfim rE r p z wn mmemo mn e on OOOOOOOUOOOOLHMHW 16.15 134179 080602 5 Kim mm LLLLLLLLLLL Gfidna mm .0 0 .m Rd m k c 0 0 gm mmmmmmw w een m e on 38641968976... num mru M 0 0 777? D. n M p H m w 0 0 00000000 w W mm h 1 mwmmmmmwmmmwmwummus fififimlfifisfim d 1 t n 77777777 0 .15 2 569 991314 667 mmmm 13451 233 3 m r m B ecvmvm O WWMMOMOOO vp leatedo mien o o 0 0 o o 0 o S w mw W mw 0.0 III" 33.033333333388799 a b h t m e............233 3 O a x P5 1 111111111 m 1d au :fluflfln n 00000 ,etWbn e S .1 "III mm m Ed r 24567 .l. .1 3 H m m w l m h w 1 6 E I 1 e 0 d m n m dds e nwmn wwm m n rw e p L m "B a HHH BCl 0012 b 80 B 212 area 0 o 000 0 u m a o m m A P h.BBBIIIGCO I O0 gW m m 10. T ITO 5 5 L5551l1111 E mm m m e w w mmmm &5 55 5 5 L I t m oi u m B m 77.7777740 1000000 I 0 [N m 6 Um m Wmmm zz mzmmaaasasa E b & H mm w G 3. r .n n r n m L P. e 6.1 f m P w m ma m emmmmmmummmnm m M .m w m m w mm w LLLLLLLLL ad e.l h mm mmmmmumummmmmmmuum v. m a :m m m m wmw LLLLLLLLLLLLLLLLL E M M w m'w N l a S 6 m. 0 3h nO Cm W m C m m .m R s s e m e u mm. H 00 %5555555000000 m P 0110 wmnw emmw emmvnmmnwnmwnmmmm n mwm e a an Rem 0p 1 1 t 8 %mm 0 W u new a rwn m.1 e t a S f S r. 6 C a 3.1 6d t 0 LII m e o t H II: AbduO .mn m u n u nh u h nfl3 e o n R 123456 Cad/0 10C 1 in the 1.9 cm.

, inclusive, were made Runs 9-12 of 55 cm inner diameter reactor. It hada preheat zone of 55 cm. packed with high silica glass Raschig rings andan un- TABLE IV 011361 Reaction mtolu- CH3B!/ Conver- Yield,tempernitn'le, 011301, Contact sion, percent ature, CHsCl, molar molartime, molar molar C. moles/hr. ratio ratio sec. basis basis and thepreheater temperature was 630 C. All data were taken from 730 C.reaction temperature runs. Tabulated below are the data obtained in theruns, including a control run.

Run

itrogen mg runs,

Yield, percent molar basis packed reaction zone of 20 cm. The remainingruns were made in a reactor packed with high silica glass Raschig rings,a 20 cm. preheat zone and a 55 cm. reaction zone. The toluene wasp-chlorotoluene, the diluent was 11 for the first three runs and steamfor. the remain the promoter was methyl bromide and the preheattemperature was held at about 630 C. in all instances. Tabulated beloware the data obtained in these runs, including eluding a control inwhich no promoter was employed. 25 a control test.

TABLE VI GHaCl/ Converp-chloro- CHaBr/ sion, Reaction toluene, CHsCl,Contact percent tempera- CHaCl, molar molar time, molar ture, C.moles/hr. ratio ratio sec. basis Run EXAMPLE V In these runs the furnacewas inverted to provide a preheat zone 55 cm. long and a reaction ofzone 20 cm.

The promoter was methyl bromide, o-chlorotoluene was 20 one reactant,the preheat temperature was held at about 630 C., nitrogen was used as adiluent and the reaction temperature in all instances was held at about730 C. Tabulated below are the data obtained in the runs, in-

0 64 7120007 WWMN67776765 7 .LLLLLL 000000000 0 9999999 M mmmlmmoooooooQ0 0 0 O 0 0 0 0 0 0 Q0 0 3 33 3 555 222 owoom mow 9.2 111 Conversion,Yield, percent percent time, molar molar sec. basis basis TABLE V oH3c10- chloro- CH Br/ toluene, CH Cl, Contact CHsCl, molar molar moles/111'.ratio ratio Run 66664.0 AmA A AI Tm 11 LLLLLL Run EXAMPLE VI In thesetests the first four runs were made with the heating furnace in theposition described in Example V. The next four runs were made in anunpacked high silica glass tube which had a length of 75 cm. and aninternal diameter of 0.9 cm., a preheat section of 20 cm. and a reactionzone 7 EXAMPLE VIII The equipment and procedural steps were the same asdescribed in the previous example. Steam was used as a diluent, toluenewas a reactant, the promoter was methyl and the reaction temperature wasmaintained at about 730 C. Contact time was calculated as .43 second. Onanalysis of the effluent, it was found that 75.1% of the o-bromotoluenewas converted. The o-bromostyrene rebromide, and the preheat temperaturewas held at about covered Was about 115% of the filial @filuenf and the630 C. Tabulated below are the data obtained in these o-chlomslylenecontent was In additlon, 53% runs. A control test is included.o-chlorotoluene was present in the efiiuent.

TABLE VIII CHaCl/ CH3Br/ Conver- Yield. Reaction toluene, CH; 01, sion,perpercent tempera- GHaCl, molar molar Contact cont momolar tnre, C.moles/hr ratio ratio time, see. lar basis basis 710 0.81 5 0 0. 52 1.8100 710 0. s1 5 0. 124 0. 51 37. 5 59. 9 710 0. s1 5 0. 21 0. 40 45. s63. 5 730 0.81 5 0. 124 0. 40 31. 5 72. 7 730 0.81 5 0. 21 0. 4s 54. 750. 1 760 0. s1 5 0. 21 0. 4s 55. 5 53. 1 730 1.12 6. 9 0.124 0. 4.4 47.a 75. 0 730 1.12 11. 2 0.124 0. 45 51. 7 71. e 730 1.12 17. 8 0.124 0.52 64. 7 s7. 4

EXAMPLE IX EXAMPLE XIlI In this series of runs the equipment andprocedural The toluene reacted was p-toluene sulfonyl fluoride. stepswere the same as described in the previous example. Nitrogen was thediluent. Preheat temperature was held p-Xylene was the substitutedtoluene used, steam was the at about 325 C. and reaction temperature washeld at diluent, the promoter was methyl bromide and the preabout 725 C.The methyl bromide-methyl chloride molar heat temperature was 630 C. Themain styrene product ratio was 1.4. The methyl chloride p toluenesulfonyl obtained was p-vinyl toluene and yields are reported forchloride molar ratio was 33 and the contact time was this compound.Small amounts of p-divinyl benzene were about .32 second. The equipmentand general procedure also obtained. The data obtained are tabulatedbelow. was the same as described in Example I.

TABLE IX Conver- Reaction CH3Cl/p- CH3BI/ sion, Yield temperaxylene,GHaCl, Contact percent percent tuxe, CHaCl, molar molar time, molarmolar C. moles/hr. ratio ratio see. basis basis 730 1. 07 5 0 0. 35 1. 7100 730 1. 07 5 0. 037 o. 35 22. 5 7s. 7 730 1. 07 5 0. 094 0. 36 30. 970. 9 730 1.143 s. 1 0. 08$ 0 36 31.0 75.8 730 1. 2 13. s 0. 083 0. 3644. s 66. 1 730 0. 034 3.3 0.107 0 36 m4 68. 0 730 1. 07 5 0. 094 0. 3532. 1 44. 5

EXAMPLE X Good yields of p-vinyl benzene sulfonyl fluoride was DiPhenylmethane was reacted in the equipment dei ;g ldentlfied by mass spectrog'scribed in the previous example. The reactant was fed at p y an 1 a rpee roscopy' a rate of .157 mole per hour, CH Cl was fed at .116 EXAMPLEXIV mole per hour. The preheat temperature was held at about l thereaction Perature was about 730 C- In this run p-tolylisocyanate was fedto the reactor with Residence time was calculated as 0.4 second. St a atnitrogen as a diluent. The preheat temperature was about a feed rate of2-2 IT101e$ P usftd as a dllllent- 500 C., and the reactor temperaturewas held at about The methyl br mide-m hyl ChlOrlde w was T 730 C. Theequipment was that described in Example I. Conversion of p y methane was40% and the ylfild The methyl chloride-p-tolylisocyanate molar ratio was5, of 1,1-d1phenylethylene was 85%. the methyl bromide-methyl chlorideratio was .11 and the EXAMPLE XI contact time was .44 second. Goodyields of p-vinyl benzeneisocyanate were obtained. The compound identityA nuxtureof 70% meta and 30% pfl i1- y was confirmed by massspectrography and infra-red specwas reacted 1n the equlpment descnbed 1nExample X. troscopy Steam was the diluent, the promoter was methylbromide EXAMPLE v and the preheat temperature was 630 C. The reactiontemperature was controlled at about 730 C. for each run. equipmentdcscrlbcd in Example I was used f r A mixture of meta andpara-divinylbenzenes was obtained thlS PHIL Pfehsai temperature W515hfikiat about C- in good yield with good conversion of thevinyltoluenes. and the feactlon tempefaturfl was maintained at about Noattempt was made to separate the divinyl isomers, but 720 C. The toluenewas p-cyanotoluene, the diluent was the presence of each isomer wasconfirmed by mass nitrogen. The methyl chloridepcyanotoluene molar ratioSpectrograph}; d V P C was 6.1 and the methyl bromide-methyl chloridemolar ratio was .086. The residence time was .47 second. EXAMPLE XIIp-Cyanostyrene, identified by mass spectrography and When o-bromotolueneis employed as a reactant, a infra-red spectroscopy, was obtained ingood yield. side reaction occurs, whereby appreciable quantities of Weclaim: o-chlorostyrene are produced. In this test, .22 mole o 1. Amethod for making a vinylbenzene compound bromotoluene, 1.14 molesmethyl chloride, 0.1 mole which comprises reacting by contacting in thevapor phase methyl bromide, and 1.54 moles of water were fed to the0.5-40 moles of methyl chloride with a mole of a toluene reactor.Preheat temperature was held at about 630 C. compound of the formula(IDH R wherein R is H, CN, or phenyl and each of X and Y is H, CN, NCO,Cl, Br, F, CH phenyl, SO F or and from about .005 to about 0.4 molebased on the methyl chloride of at least one of methyl bromide, methyliodide, hydrogen bromide, bromine or iodine, at a temperature of fromabout 650 to about 1000 C.

2. The method of claim 1 wherein an inert diluent is added to thereaction mixture.

3. The method of claim 1 in which methyl bromide is added to thereaction mixture.

4. The method of claim 1 in which methyl iodide is added to the reactionmixture.

5. The method of claim 1 in which hydrogen bromide is added to thereaction mixture.

6. The method of claim 1 in which elemental bromine is added to thereaction mixture.

7. The method of claim 1 in which elemental iodine is added to thereaction mixture.

8. The method of claim 1 in which R is CN.

9. The method of claim 1 in which one of X and Y is CN and the other isH.

10. The method of claim 1 in which one of X and Y is Cl and the other isH.

11. The method of claim 1 in which X is NCO in the meta or para positionand Y and R each is H.

12. The method of claim 1 in which one of X and Y is F and the other isH.

13. The method of claim 1 in which R, X and Y each is H.

14. The method of claim 1 in which R is H and one of X and Y is CH andthe other is H.

15. The method of claim 1 in which R is phenyl.

16. The method of claim 1 in which R is H and one of X and Y is CH=CHand the other is H.

17. The method of claim 1 in Which one of X and Y is SO F and the otheris H, and R is H.

References Cited UNITED STATES PATENTS 3,219,711 11/1965 Borkowski eta1. 260669 3,303,229 2/1967 De Rossett 260669 CURTIS R. DAVIS, PrimaryExaminer US. Cl. X.R. 260-465, 539, 650

